I've played the piano for many, many hours a day for the last two and a half years after playing in a desultory fashion when I was little. Recently I just stopped.
The reason I stopped is because, maintaining your skills requires hours of practice every day. In addition, I'm unenthusiastic about most piano literature, and am more interested in symphonic music, like Wagner, R. Strauss and Debussy's orchestral music. When some of the transcriptions of those work really well for piano I dig playing them, but that is pretty rare (that they work well on piano). So why should I devote thousands of hours of my life to music I'm not even partial to?